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Regeneración de bosques tropicales fragmentados del Beni, Bolivia

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... The study was carried out at the Beni Biological Station Biosphere Reserve (EBB), Bolivia ( phalerata (Arecaceae), Eugenia patricii (Myrtaceae), Machaerium hirtum (Fabaceae), A. murumuru and Triplaris americana (Poligonaceae ) as the most frequent trees (Simonetti et al., 2001). We chose two areas of continuous forest (Campo Mono and Marimonos) and two forest fragments (Mid and Taita A). ...
... Triplaris americana (Polygonaceae) is a common dioecious myrmecophytic tree among the most frequent tree species at study site and exhibits scarce recruitment of both con-and heterospecific seedlings under its canopy (Simonetti et al., 2001). The abundance of heterospecific seedlings within 2 m of the canopy of T. americana is only half that found more than 2 m from the canopy (J.A. Simonetti unpublished data). ...
... Like other species, T. americana grows in forest fragments and in continuous forest, and in both kinds of sites recruitment of conspecific seedlings under its canopy is also relatively low. In forest fragments, about 3.3% of all seedlings grow under a parental T. americana tree, whereas in the continuous forest no conspecific seedlings exist growing under the canopy of these trees (Simonetti et al., 2001), suggesting that the occupation rates of Triplaris trees by Pseudomyrmex ants could be different between both habitats. The zone of low seedling recruitment coincides with the maximum patrolling distance of Pseudomyrmex triplarinus Weddell (Pseudomyrmecinae), the ant species which commonly colonizes T. americana trees (Oliveira et al., 1987). ...
Article
We compared the relative importance of chemical alellopathy, pruning behaviour of resident ants and other non-related agents to ant-plant mutualism for seedling establishment beneath Triplaris americana L. (Polygonaceae), a myrmecophyte plant. We also included a preliminary analysis of effects of fragmentation on these ecological processes. Seeds and seedlings of Theobroma cacao L. (Sterculiaceae) were used as the target species in all experiments. Leaf-tissue extracts of the myrmecophyte plant did not inhibit germination of cacao seeds. Resident Pseudomyrmex triplarinus Weddell (Pseudomyrmecinae) ants did not remove seeds under the canopy of their host plants. The main seed consumer was the leaf-cutting ant Atta sexdens L. (Myrmicinae). Leaves of cacao seedlings were partially or totally pruned by Pseudomyrmex ants mainly in forest fragments studied. We offer evidence pointing to the possibility that the absence of seedlings beneath Triplaris may result from effects of both ant species. We discuss the benefits of pruning behaviour for the resident ant colony and the effects of ant–ant interactions on seedling establishment beneath this ant-plant system.
... Other mechanisms may also hinder forest regeneration in watersheds with replacement. For example, lower seed production is associated with lower density of adult and larger trees ( Simonetti et al. 2001). Also, competition with exotic herbaceous species resulting from the invasions observed in remnant riparian forest could reduce regeneration ( Hobbs 2001;Kanowski et al. 2003;Huth and Wagner 2006;Zhu et al. 2014). ...
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Background: As riparian habitats are legally protected, they have been maintained even in areas where extensive reforestation by exotic species occurred in areas surrounding riparian environments. However, the extent to which the riparian plant communities have been affected by the replacement of native forest on slopes has rarely been investigated. Aims: In this study, we evaluated the effects of replacement of native forest by Pinus radiata plantations, on the diversity and structure of plant communities of remnant forests preserved in riparian habitats. Methods: We selected five watersheds with native forest and five watersheds where the native forest had been replaced by pine plantations preserving riparian forests and compared composition, diversity and structure of riparian vegetation. Results: In watersheds with pine plantation, riparian forests had lower adult tree density, tree cover, diversity and regeneration and higher shrub cover, diversity of herb species and diversity and richness of exotic species than riparian forests with abutting native forest. Conclusions: The results suggest that the replacement of native forest by pine plantations negatively affects the diversity and structure of riparian forest. However, in other respects (e.g. shrub and climber richness), these habitats are not affected and they contribute significantly to the biodiversity conservation.
... La densidad total para todas las especies fue de 0.01 ind/m 2 es menor comparado a los que reportan Simonetti et al. (2001) de 1.384 plántulas, Martínez-Ramos y Soto-Castro (1993) de 11.6 plántulas en los Tuxtlas, Veracruz. Esta baja densidad encontrada puede deberse a las condiciones fisiográficas del sitio. ...
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The tropical rainforest is one of the best developed and most complex ecosystems, yet is undergoing very rapid deterioration. The alternative course of recovering it requires knowledge of the process of regeneration. The objective of this research was to evaluate the process of natural regeneration in a high evergreen forest relict in Agua Blanca State Park, Macuspana, Tabasco, as well as to learn the floristic composition, measure species diversity and floristic similarity, and analyze physical factors (litter depth, litter cover, crown cover, soil moisture, and pH). Two sampling units of 50 X 50 m were established, each divided into 25 subunits of 10 X 10 m, in which four plots of 1 X 1 m were subsequently set up at random. To conduct the regeneration study, all individuals ¿1.30 m and ¿1.30 m were censused and their lifeform determined. Measurements of physical factors were carried out in each 1 X 1 m plot. A total of 152 seedlings representing 46 species and 20 families are reported. Rinorea guatemalensis was the species with the highest number of seedlings. The index of diversity was H' = 3.7 in sampling unit 1 and H' = 3.0 for unit 2. Floristic similarity was 27%. There was no correlation between the number of individuals and number of species for each of the factors analyzed. We conclude that the high evergreen forest relict is in the process of regeneration as the species of tree seedlings reported are characteristic of a primary forest.
... Many of the remnants of dry forests have been subjected to anthropogenic fragmentation , and hence abiotic changes that result from reductions in forest patch area are likely to produce declines in local diversity and density of native trees and other species (e.g. Bennett, 2003; Cadenasso and Pickett, 2001; Echeverría et al., 2006; Drinnan, 2005; Hersperger and Forman, 2003; Hobbs, 2001; Holt et al., 1995; Honnay et al., 1999; Laurance et al., 1998a Laurance et al., , 1998b Laurance et al., , 2001 Matlack, 1994; Quinn and Harrison, 1988; Simonetti et al., 2001; Soulé et al., 1992; Tabarelli et al., 1999; Willson et al., 2001 ). However, the typical effects of patch area on species richness have not always been found, for example in the case of South African Mediterranean woodlands (Kemper et al., 1999). ...
... As result of these disturbances, forest fragmentation has become a widespread phenomenon of terrestrial biomes. Fragmentation can induce long-term changes in forest composition through many processes such as the richness reduction that is frequently associated with habitat loss (Williams-Linera et al., 1998; Fahrig, 2001; Hill and Curran, 2001; Simonetti et al., 2001), the invasion of species from the vegetation matrix surrounding the fragments (Lovejoy et al., 1986; Tabarelli et al., 1999; Fox et al., 1997; Honnay et al., 2002), or differential recruitment along an edge-center environmental gradient (Chen et al., 1992; Laurance et al., 1998; Oosterhoorn and Kappelle, 2000; Harper et al., 2005). In this way, even if a fragment conserves its size, successional changes could result in a composition vastly different from the original forest ( Oliveira-Filho et al., 1997). ...
Article
In the fragmented Maulino forest (in Central Chile), differences in the relative frequencies of species between seedlings and mature trees are strong indicators of a changing replacement dynamics in the community. Stationary Markov chain models predict that the future tree composition such Maulino forest fragments will differ from that of continuous, intact forest. We found that the persistence probability was highest for Aristotelia chilensis and lowest for Nothofagus glauca. These two tree species are the most affected by fragmentation, and changes in their abundances appear to be the main drivers of the long-term change in stand composition. The aim of our study was to test if the management of just these two species would be sufficient to avoid long-term changes in the composition of forest fragments or would recover their composition toward a state more similar to the continuous forest. For this purpose, we constructed a Markov matrix model from published information, and calculated the future stable stand composition under different management simulations: (1) reduction of A. chilensis recruitment, (2) increased recruitment of N. glauca, and (3) a combined treatment. To evaluate the effectiveness of management treatments, the future composition of fragments was compared with the composition expected for continuous (i.e., undisturbed) Maulino forest. We performed a sensitivity analysis of the stable composition in order to assess the intensity of changes in the future composition driven by the treatments, and to determine to what extend the recruitment of other coexisting species contributes to changes in relative frequencies of A. chilensis and N. glauca.
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The high degree of isolation of forest “islands” relative to “continental” forested areas creates a naturally fragmented landscape in the savanna ecosystem. Because fragmentation can affect the intensity and quality of biological interactions (e.g., seed dispersal) we examined the abundance and species richness of seed rain produced by birds and bats in three different parts of forest islands (center, edge, and exterior) located at the Estación Biológica del Beni, Bolivia. Despite the fact that we found higher species density of seeds in the seed rain at the center of forest islands, when comparing species richness corrected for observed differences in density, species richness was higher at the edge of islands. The three parts of the islands did not differ in total number of seeds. Three genera (Byrsonima, Ficus, and Piper) contributed the most seeds to the seed rain. We found differences in the abundance of dispersed seeds probably because of the variation related with the disturbance line, where the savanna matrix interacts with the forest islands. Carollia perspicillata, Carollia brevicauda, and Sturnira lilium were the bats that contributed most to seed dispersal within forest islands, and Schistochlamys melanopis and Tyranneutes stolzmanni were the most important birds. The movement of seeds produced by bats and birds within forest islands of the savanna is crucial to assure the continuity of ecological process and dynamics of these forest islands.
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